// Tencent is pleased to support the open source community by making RapidJSON available.
// 
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software distributed 
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
// specific language governing permissions and limitations under the License.

#ifndef RAPIDJSON_ENCODINGS_H_
#define RAPIDJSON_ENCODINGS_H_

#include "rapidjson.h"

#ifdef _MSC_VER
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(4244) // conversion from 'type1' to 'type2', possible loss of data
RAPIDJSON_DIAG_OFF(4702)  // unreachable code
#elif defined(__GNUC__)
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(effc++)
RAPIDJSON_DIAG_OFF(overflow)
#endif

RAPIDJSON_NAMESPACE_BEGIN

///////////////////////////////////////////////////////////////////////////////
// Encoding

/*! \class rapidjson::Encoding
    \brief Concept for encoding of Unicode characters.

\code
concept Encoding {
    typename Ch;    //! Type of character. A "character" is actually a code unit in unicode's definition.

    enum { supportUnicode = 1 }; // or 0 if not supporting unicode

    //! \brief Encode a Unicode codepoint to an output stream.
    //! \param os Output stream.
    //! \param codepoint An unicode codepoint, ranging from 0x0 to 0x10FFFF inclusively.
    template<typename OutputStream>
    static void Encode(OutputStream& os, unsigned codepoint);

    //! \brief Decode a Unicode codepoint from an input stream.
    //! \param is Input stream.
    //! \param codepoint Output of the unicode codepoint.
    //! \return true if a valid codepoint can be decoded from the stream.
    template <typename InputStream>
    static bool Decode(InputStream& is, unsigned* codepoint);

    //! \brief Validate one Unicode codepoint from an encoded stream.
    //! \param is Input stream to obtain codepoint.
    //! \param os Output for copying one codepoint.
    //! \return true if it is valid.
    //! \note This function just validating and copying the codepoint without actually decode it.
    template <typename InputStream, typename OutputStream>
    static bool Validate(InputStream& is, OutputStream& os);

    // The following functions are deal with byte streams.

    //! Take a character from input byte stream, skip BOM if exist.
    template <typename InputByteStream>
    static CharType TakeBOM(InputByteStream& is);

    //! Take a character from input byte stream.
    template <typename InputByteStream>
    static Ch Take(InputByteStream& is);

    //! Put BOM to output byte stream.
    template <typename OutputByteStream>
    static void PutBOM(OutputByteStream& os);

    //! Put a character to output byte stream.
    template <typename OutputByteStream>
    static void Put(OutputByteStream& os, Ch c);
};
\endcode
*/

///////////////////////////////////////////////////////////////////////////////
// UTF8

//! UTF-8 encoding.
/*! http://en.wikipedia.org/wiki/UTF-8
    http://tools.ietf.org/html/rfc3629
    \tparam CharType Code unit for storing 8-bit UTF-8 data. Default is char.
    \note implements Encoding concept
*/
    template<typename CharType = char>
    struct UTF8 {
        typedef CharType Ch;

        enum {
            supportUnicode = 1
        };

        template<typename OutputStream>
        static void Encode(OutputStream &os, unsigned codepoint) {
            if (codepoint <= 0x7F)
                os.Put(static_cast<Ch>(codepoint & 0xFF));
            else if (codepoint <= 0x7FF) {
                os.Put(static_cast<Ch>(0xC0 | ((codepoint >> 6) & 0xFF)));
                os.Put(static_cast<Ch>(0x80 | ((codepoint & 0x3F))));
            } else if (codepoint <= 0xFFFF) {
                os.Put(static_cast<Ch>(0xE0 | ((codepoint >> 12) & 0xFF)));
                os.Put(static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
                os.Put(static_cast<Ch>(0x80 | (codepoint & 0x3F)));
            } else {
                RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
                os.Put(static_cast<Ch>(0xF0 | ((codepoint >> 18) & 0xFF)));
                os.Put(static_cast<Ch>(0x80 | ((codepoint >> 12) & 0x3F)));
                os.Put(static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
                os.Put(static_cast<Ch>(0x80 | (codepoint & 0x3F)));
            }
        }

        template<typename InputStream>
        static bool Decode(InputStream &is, unsigned *codepoint) {
#define COPY() c = is.Take(); *codepoint = (*codepoint << 6) | ((unsigned char)c & 0x3Fu)
#define TRANS(mask) result &= ((GetRange((unsigned char)c) & mask) != 0)
#define TAIL() COPY(); TRANS(0x70)
            Ch c = is.Take();
            if (!(c & 0x80)) {
                *codepoint = (unsigned char) c;
                return true;
            }

            unsigned char type = GetRange((unsigned char) c);
            *codepoint = (0xFF >> type) & (unsigned char) c;
            bool result = true;
            switch (type) {
                case 2:
                TAIL();
                    return result;
                case 3:
                TAIL();
                    TAIL();
                    return result;
                case 4:
                COPY();
                    TRANS(0x50);
                    TAIL();
                    return result;
                case 5:
                COPY();
                    TRANS(0x10);
                    TAIL();
                    TAIL();
                    return result;
                case 6:
                TAIL();
                    TAIL();
                    TAIL();
                    return result;
                case 10:
                COPY();
                    TRANS(0x20);
                    TAIL();
                    return result;
                case 11:
                COPY();
                    TRANS(0x60);
                    TAIL();
                    TAIL();
                    return result;
                default:
                    return false;
            }
#undef COPY
#undef TRANS
#undef TAIL
        }

        template<typename InputStream, typename OutputStream>
        static bool Validate(InputStream &is, OutputStream &os) {
#define COPY() os.Put(c = is.Take())
#define TRANS(mask) result &= ((GetRange((unsigned char)c) & mask) != 0)
#define TAIL() COPY(); TRANS(0x70)
            Ch c;
            COPY();
            if (!(c & 0x80))
                return true;

            bool result = true;
            switch (GetRange((unsigned char) c)) {
                case 2:
                TAIL();
                    return result;
                case 3:
                TAIL();
                    TAIL();
                    return result;
                case 4:
                    COPY();
                    TRANS(0x50);
                    TAIL();
                    return result;
                case 5:
                    COPY();
                    TRANS(0x10);
                    TAIL();
                    TAIL();
                    return result;
                case 6:
                TAIL();
                    TAIL();
                    TAIL();
                    return result;
                case 10:
                    COPY();
                    TRANS(0x20);
                    TAIL();
                    return result;
                case 11:
                    COPY();
                    TRANS(0x60);
                    TAIL();
                    TAIL();
                    return result;
                default:
                    return false;
            }
#undef COPY
#undef TRANS
#undef TAIL
        }

        static unsigned char GetRange(unsigned char c) {
            // Referring to DFA of http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
            // With new mapping 1 -> 0x10, 7 -> 0x20, 9 -> 0x40, such that AND operation can test multiple types.
            static const unsigned char type[] = {
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,
                    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
                    0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                    0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                    8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
                    10, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 3, 3, 11, 6, 6, 6, 5, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
            };
            return type[c];
        }

        template<typename InputByteStream>
        static CharType TakeBOM(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            Ch c = Take(is);
            if ((unsigned char) c != 0xEFu) return c;
            c = is.Take();
            if ((unsigned char) c != 0xBBu) return c;
            c = is.Take();
            if ((unsigned char) c != 0xBFu) return c;
            c = is.Take();
            return c;
        }

        template<typename InputByteStream>
        static Ch Take(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            return is.Take();
        }

        template<typename OutputByteStream>
        static void PutBOM(OutputByteStream &os) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(0xEFu);
            os.Put(0xBBu);
            os.Put(0xBFu);
        }

        template<typename OutputByteStream>
        static void Put(OutputByteStream &os, Ch c) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(static_cast<typename OutputByteStream::Ch>(c));
        }
    };

///////////////////////////////////////////////////////////////////////////////
// UTF16

//! UTF-16 encoding.
/*! http://en.wikipedia.org/wiki/UTF-16
    http://tools.ietf.org/html/rfc2781
    \tparam CharType Type for storing 16-bit UTF-16 data. Default is wchar_t. C++11 may use char16_t instead.
    \note implements Encoding concept

    \note For in-memory access, no need to concern endianness. The code units and code points are represented by CPU's endianness.
    For streaming, use UTF16LE and UTF16BE, which handle endianness.
*/
    template<typename CharType = wchar_t>
    struct UTF16 {
        typedef CharType Ch;
        RAPIDJSON_STATIC_ASSERT(sizeof(Ch) >= 2);

        enum {
            supportUnicode = 1
        };

        template<typename OutputStream>
        static void Encode(OutputStream &os, unsigned codepoint) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 2);
            if (codepoint <= 0xFFFF) {
                RAPIDJSON_ASSERT(
                        codepoint < 0xD800 || codepoint > 0xDFFF); // Code point itself cannot be surrogate pair
                os.Put(static_cast<typename OutputStream::Ch>(codepoint));
            } else {
                RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
                unsigned v = codepoint - 0x10000;
                os.Put(static_cast<typename OutputStream::Ch>((v >> 10) | 0xD800));
                os.Put((v & 0x3FF) | 0xDC00);
            }
        }

        template<typename InputStream>
        static bool Decode(InputStream &is, unsigned *codepoint) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 2);
            Ch c = is.Take();
            if (c < 0xD800 || c > 0xDFFF) {
                *codepoint = c;
                return true;
            } else if (c <= 0xDBFF) {
                *codepoint = (c & 0x3FF) << 10;
                c = is.Take();
                *codepoint |= (c & 0x3FF);
                *codepoint += 0x10000;
                return c >= 0xDC00 && c <= 0xDFFF;
            }
            return false;
        }

        template<typename InputStream, typename OutputStream>
        static bool Validate(InputStream &is, OutputStream &os) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 2);
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 2);
            Ch c;
            os.Put(c = is.Take());
            if (c < 0xD800 || c > 0xDFFF)
                return true;
            else if (c <= 0xDBFF) {
                os.Put(c = is.Take());
                return c >= 0xDC00 && c <= 0xDFFF;
            }
            return false;
        }
    };

//! UTF-16 little endian encoding.
    template<typename CharType = wchar_t>
    struct UTF16LE : UTF16<CharType> {
        template<typename InputByteStream>
        static CharType TakeBOM(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            CharType c = Take(is);
            return (unsigned short) c == 0xFEFFu ? Take(is) : c;
        }

        template<typename InputByteStream>
        static CharType Take(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            CharType c = (unsigned char) is.Take();
            c |= (unsigned char) is.Take() << 8;
            return c;
        }

        template<typename OutputByteStream>
        static void PutBOM(OutputByteStream &os) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(0xFFu);
            os.Put(0xFEu);
        }

        template<typename OutputByteStream>
        static void Put(OutputByteStream &os, CharType c) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(c & 0xFFu);
            os.Put((c >> 8) & 0xFFu);
        }
    };

//! UTF-16 big endian encoding.
    template<typename CharType = wchar_t>
    struct UTF16BE : UTF16<CharType> {
        template<typename InputByteStream>
        static CharType TakeBOM(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            CharType c = Take(is);
            return (unsigned short) c == 0xFEFFu ? Take(is) : c;
        }

        template<typename InputByteStream>
        static CharType Take(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            CharType c = (unsigned char) is.Take() << 8;
            c |= (unsigned char) is.Take();
            return c;
        }

        template<typename OutputByteStream>
        static void PutBOM(OutputByteStream &os) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(0xFEu);
            os.Put(0xFFu);
        }

        template<typename OutputByteStream>
        static void Put(OutputByteStream &os, CharType c) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put((c >> 8) & 0xFFu);
            os.Put(c & 0xFFu);
        }
    };

///////////////////////////////////////////////////////////////////////////////
// UTF32

//! UTF-32 encoding. 
/*! http://en.wikipedia.org/wiki/UTF-32
    \tparam CharType Type for storing 32-bit UTF-32 data. Default is unsigned. C++11 may use char32_t instead.
    \note implements Encoding concept

    \note For in-memory access, no need to concern endianness. The code units and code points are represented by CPU's endianness.
    For streaming, use UTF32LE and UTF32BE, which handle endianness.
*/
    template<typename CharType = unsigned>
    struct UTF32 {
        typedef CharType Ch;
        RAPIDJSON_STATIC_ASSERT(sizeof(Ch) >= 4);

        enum {
            supportUnicode = 1
        };

        template<typename OutputStream>
        static void Encode(OutputStream &os, unsigned codepoint) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 4);
            RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
            os.Put(codepoint);
        }

        template<typename InputStream>
        static bool Decode(InputStream &is, unsigned *codepoint) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 4);
            Ch c = is.Take();
            *codepoint = c;
            return c <= 0x10FFFF;
        }

        template<typename InputStream, typename OutputStream>
        static bool Validate(InputStream &is, OutputStream &os) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 4);
            Ch c;
            os.Put(c = is.Take());
            return c <= 0x10FFFF;
        }
    };

//! UTF-32 little endian enocoding.
    template<typename CharType = unsigned>
    struct UTF32LE : UTF32<CharType> {
        template<typename InputByteStream>
        static CharType TakeBOM(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            CharType c = Take(is);
            return (unsigned) c == 0x0000FEFFu ? Take(is) : c;
        }

        template<typename InputByteStream>
        static CharType Take(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            CharType c = (unsigned char) is.Take();
            c |= (unsigned char) is.Take() << 8;
            c |= (unsigned char) is.Take() << 16;
            c |= (unsigned char) is.Take() << 24;
            return c;
        }

        template<typename OutputByteStream>
        static void PutBOM(OutputByteStream &os) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(0xFFu);
            os.Put(0xFEu);
            os.Put(0x00u);
            os.Put(0x00u);
        }

        template<typename OutputByteStream>
        static void Put(OutputByteStream &os, CharType c) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(c & 0xFFu);
            os.Put((c >> 8) & 0xFFu);
            os.Put((c >> 16) & 0xFFu);
            os.Put((c >> 24) & 0xFFu);
        }
    };

//! UTF-32 big endian encoding.
    template<typename CharType = unsigned>
    struct UTF32BE : UTF32<CharType> {
        template<typename InputByteStream>
        static CharType TakeBOM(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            CharType c = Take(is);
            return (unsigned) c == 0x0000FEFFu ? Take(is) : c;
        }

        template<typename InputByteStream>
        static CharType Take(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            CharType c = (unsigned char) is.Take() << 24;
            c |= (unsigned char) is.Take() << 16;
            c |= (unsigned char) is.Take() << 8;
            c |= (unsigned char) is.Take();
            return c;
        }

        template<typename OutputByteStream>
        static void PutBOM(OutputByteStream &os) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(0x00u);
            os.Put(0x00u);
            os.Put(0xFEu);
            os.Put(0xFFu);
        }

        template<typename OutputByteStream>
        static void Put(OutputByteStream &os, CharType c) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put((c >> 24) & 0xFFu);
            os.Put((c >> 16) & 0xFFu);
            os.Put((c >> 8) & 0xFFu);
            os.Put(c & 0xFFu);
        }
    };

///////////////////////////////////////////////////////////////////////////////
// ASCII

//! ASCII encoding.
/*! http://en.wikipedia.org/wiki/ASCII
    \tparam CharType Code unit for storing 7-bit ASCII data. Default is char.
    \note implements Encoding concept
*/
    template<typename CharType = char>
    struct ASCII {
        typedef CharType Ch;

        enum {
            supportUnicode = 0
        };

        template<typename OutputStream>
        static void Encode(OutputStream &os, unsigned codepoint) {
            RAPIDJSON_ASSERT(codepoint <= 0x7F);
            os.Put(static_cast<Ch>(codepoint & 0xFF));
        }

        template<typename InputStream>
        static bool Decode(InputStream &is, unsigned *codepoint) {
            unsigned char c = static_cast<unsigned char>(is.Take());
            *codepoint = c;
            return c <= 0X7F;
        }

        template<typename InputStream, typename OutputStream>
        static bool Validate(InputStream &is, OutputStream &os) {
            unsigned char c = is.Take();
            os.Put(c);
            return c <= 0x7F;
        }

        template<typename InputByteStream>
        static CharType TakeBOM(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            Ch c = Take(is);
            return c;
        }

        template<typename InputByteStream>
        static Ch Take(InputByteStream &is) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
            return is.Take();
        }

        template<typename OutputByteStream>
        static void PutBOM(OutputByteStream &os) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            (void) os;
        }

        template<typename OutputByteStream>
        static void Put(OutputByteStream &os, Ch c) {
            RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
            os.Put(static_cast<typename OutputByteStream::Ch>(c));
        }
    };

///////////////////////////////////////////////////////////////////////////////
// AutoUTF

//! Runtime-specified UTF encoding type of a stream.
    enum UTFType {
        kUTF8 = 0,      //!< UTF-8.
        kUTF16LE = 1,   //!< UTF-16 little endian.
        kUTF16BE = 2,   //!< UTF-16 big endian.
        kUTF32LE = 3,   //!< UTF-32 little endian.
        kUTF32BE = 4    //!< UTF-32 big endian.
    };

//! Dynamically select encoding according to stream's runtime-specified UTF encoding type.
/*! \note This class can be used with AutoUTFInputtStream and AutoUTFOutputStream, which provides GetType().
*/
    template<typename CharType>
    struct AutoUTF {
        typedef CharType Ch;

        enum {
            supportUnicode = 1
        };

#define RAPIDJSON_ENCODINGS_FUNC(x) UTF8<Ch>::x, UTF16LE<Ch>::x, UTF16BE<Ch>::x, UTF32LE<Ch>::x, UTF32BE<Ch>::x

        template<typename OutputStream>
        RAPIDJSON_FORCEINLINE static void Encode(OutputStream &os, unsigned codepoint) {
            typedef void (*EncodeFunc)(OutputStream &, unsigned);
            static const EncodeFunc f[] = {RAPIDJSON_ENCODINGS_FUNC(Encode)};
            (*f[os.GetType()])(os, codepoint);
        }

        template<typename InputStream>
        RAPIDJSON_FORCEINLINE static bool Decode(InputStream &is, unsigned *codepoint) {
            typedef bool (*DecodeFunc)(InputStream &, unsigned *);
            static const DecodeFunc f[] = {RAPIDJSON_ENCODINGS_FUNC(Decode)};
            return (*f[is.GetType()])(is, codepoint);
        }

        template<typename InputStream, typename OutputStream>
        RAPIDJSON_FORCEINLINE static bool Validate(InputStream &is, OutputStream &os) {
            typedef bool (*ValidateFunc)(InputStream &, OutputStream &);
            static const ValidateFunc f[] = {RAPIDJSON_ENCODINGS_FUNC(Validate)};
            return (*f[is.GetType()])(is, os);
        }

#undef RAPIDJSON_ENCODINGS_FUNC
    };

///////////////////////////////////////////////////////////////////////////////
// Transcoder

//! Encoding conversion.
    template<typename SourceEncoding, typename TargetEncoding>
    struct Transcoder {
        //! Take one Unicode codepoint from source encoding, convert it to target encoding and put it to the output stream.
        template<typename InputStream, typename OutputStream>
        RAPIDJSON_FORCEINLINE static bool Transcode(InputStream &is, OutputStream &os) {
            unsigned codepoint;
            if (!SourceEncoding::Decode(is, &codepoint))
                return false;
            TargetEncoding::Encode(os, codepoint);
            return true;
        }

        //! Validate one Unicode codepoint from an encoded stream.
        template<typename InputStream, typename OutputStream>
        RAPIDJSON_FORCEINLINE static bool Validate(InputStream &is, OutputStream &os) {
            return Transcode(is, os);   // Since source/target encoding is different, must transcode.
        }
    };

//! Specialization of Transcoder with same source and target encoding.
    template<typename Encoding>
    struct Transcoder<Encoding, Encoding> {
        template<typename InputStream, typename OutputStream>
        RAPIDJSON_FORCEINLINE static bool Transcode(InputStream &is, OutputStream &os) {
            os.Put(is.Take());  // Just copy one code unit. This semantic is different from primary template class.
            return true;
        }

        template<typename InputStream, typename OutputStream>
        RAPIDJSON_FORCEINLINE static bool Validate(InputStream &is, OutputStream &os) {
            return Encoding::Validate(is, os);  // source/target encoding are the same
        }
    };

RAPIDJSON_NAMESPACE_END

#if defined(__GNUC__) || defined(_MSV_VER)
RAPIDJSON_DIAG_POP
#endif

#endif // RAPIDJSON_ENCODINGS_H_
